I tried another thing.
Usually I use Habpanel by safari as a link on my homescreen (I assume safari works in the background)
However, this link (as mentioned above) has problems displaying the itemState correctly, but shows my custom icons perfectly (copied into smartphone-set folder in assets and changed the smartphone-set file accordingly)
Running HABpanel directy in safari shows the itemState correctly but not the icons.
Do you have any idea why safari is not able to localize the icons?